/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2010 The Boeing Company
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Tom Goff <thomas.goff@boeing.com>
 */

#ifndef WIN32_FD_READER_H
#define WIN32_FD_READER_H

#include <cstdint>

#include "callback.h"
#include "system-thread.h"
#include "event-id.h"
#include <BaseTsd.h>
typedef SSIZE_T ssize_t;

/**
 * \file
 * \ingroup system
 * ns3::FdReader declaration.
 */

namespace ns3 {

/**
 * \ingroup system
 * \brief A class that asynchronously reads from a file descriptor.
 *
 * This class can be used to start a system thread that reads from a
 * given file descriptor and invokes a given callback when data is
 * received.  This class handles thread management automatically but
 * the \p DoRead() method must be implemented by a subclass.
 */
    class FdReader : public SimpleRefCount<FdReader>
    {
    public:
        /** Constructor. */
        FdReader();
        /** Destructor. */
        virtual ~FdReader();

        /**
         * Start a new read thread.
         *
         * \param [in] fd A valid file descriptor open for reading.
         *
         * \param [in] readCallback A callback to invoke when new data is
         * available.
         */
        void Start (int fd, Callback<void, uint8_t *, ssize_t> readCallback);

        /**
         * Stop the read thread and reset internal state.  This does not
         * close the file descriptor used for reading.
         */
        void Stop (void);

        static bool winsock_initialized;
    protected:

        /**
         * \brief A structure representing data read.
         */
        struct Data
        {
            /** Default constructor, with null buffer and zero length. */
            Data () : m_buf (0), m_len (0) {}
            /**
             * Construct from a buffer of a given length.
             *
             * \param [in] buf The buffer.
             * \param [in] len The size of the buffer, in bytes.
             */
            Data (uint8_t *buf, ssize_t len) : m_buf (buf), m_len (len) {}
            /** The read data buffer. */
            uint8_t *m_buf;
            /** The size of the read data buffer, in bytes. */
            ssize_t m_len;
        };

        /**
         * \brief The read implementation.
         *
         * The value of \p m_len returned controls further processing.  The
         * callback function is only invoked when \p m_len is positive; any
         * data read is not processed when \p m_len is negative; reading
         * stops when \p m_len is zero.
         *
         * The management of memory associated with \p m_buf must be
         * compatible with the read callback.
         *
         * \return A structure representing what was read.
         */
        virtual FdReader::Data DoRead (void) = 0;

        /**
         * \brief The file descriptor to read from.
         */
        int m_fd;

    private:

        /** The asynchronous function which performs the read. */
        void Run (void);
        /** Event handler scheduled for destroy time to halt the thread. */
        void DestroyEvent (void);

        /** The main thread callback function to invoke when we have data. */
        Callback<void, uint8_t *, ssize_t> m_readCallback;

        /** The thread doing the read, created and launched by Start(). */
        Ptr<SystemThread> m_readThread;

        /** Pipe used to signal events between threads. */
        int m_evpipe[2];
        /** Signal the read thread to stop. */
        bool m_stop;

        /**
         * The event scheduled for destroy time which will invoke DestroyEvent
         * and halt the thread.
         */
        EventId m_destroyEvent;
    };

} // namespace ns3

#endif /* WIN32_FD_READER_H */